Many modern hair products are tailored to provide benefits to specific properties of hair, such as fineness, curliness, dryness, greasiness, level of damage, and so on. For a consumer to choose the right hair products, he/she must have knowledge of the condition of their hair. In order to achieve this knowledge, it is advantageous to carry out an assessment of the hair.
Methods of measuring roughness and other properties of surfaces are described in the following prior art.
US 2003/0234650 discloses a comparator for surface finishes for the evaluation of SPI surface finishes with the turbine steam path. An embodiment comprises a small particle impingement comparator comprising a plurality of sample cells arranged side-by-side in ascending order of roughness from 1190 micro-inches to 6950 micro-inches.
Microsyst Tecnol (2011) 17:1153-1160, describes a sensor system for the evaluation of hair, under dry and wet conditions. The sensor consists of an acrylic base, a silicone runner and a polyvinylidene fluoride film. A surface projection is put on the PVDF film. It is used to measure a range of hair feel properties including roughness, slippery-smooth, smooth, squeak and moist.
Our co-pending patent application, PCT/EP2014/056104 discloses a self-assessment device comprising a series of rough patches of increasing roughness and which may be contacted by user and compared with the roughness of a hair sample in order to provide an indication to the user as to the relative state of the hair sample.
US2002/0140936 discloses a system comprising a plurality of comparison samples configured to substantially simulate the appearance of a keratinous element. Each comparison sample may be configured to substantially simulate both a colour and an appearance characteristic other than colour of the keratinous element.
Despite the prior art there remains a need for improved devices that provide accurate yet simple means for assessing the state of hair fibres and for devices that enable more than one property of hair to be measured simultaneously. The prior art only provides devices where properties are measured using a single sensory aspect, namely touch or appearance. We have now found that by combining the use of the different sensory aspects of feel and appearance, a more useful and insightful assessment is made. We have found that by aligning two scales of properties pertaining to the two different aspects, roughness and shine, the relationship between them is indicated to the user, thus enabling insight as well as more suitable, targeted treatment regimes to be recommended.